Direct deposition of agents interstitially can be of significant beneficial value and is effected by needle or catheter use. Tissue injection has long been a popular, relatively non-invasive means for the direct introduction of various medicaments and other fluids. It is becoming more popular as a means for non-invasive delivery of pharmaceutical preparations of cytotoxic drugs and drug delivery systems into solid tumor because it minimizes tissue trauma, increases local efficacy, and decreases side effects and systemic toxicity. Direct injection, using needles, catheters, or a combined deposition system, is a practical delivery strategy for antiangiogenesis, tumor embolization, hemostasis, and direct cell kill. Direct interstitial chemotherapy is slowly gaining ground among the medical community. A growing number of research papers and clinical reports published during the years 1990-2000 have shown improved efficacy and reduced toxicity in animal as well as in human tumors (E. P. Goldberg et al., J. Pharm Pharmacol 54(2):159-180 (2002)).
Most commercial injection systems use needles or catheters which are incapable of preventing backflow of fluid out of the entry-track. These systems suffer from the difficulties associated with lack of a steady means of securing to a target. Current securing and anti backflow injecting systems described in the literature are either too aggressive to tissues or do not insure tight and steady bonding. In addition, injection techniques are operator dependant. Such techniques rely upon perceived tumor margins and mass, subjective assessment of the number of sites of puncture to cover the entire visible mass, and subjective assessment of the liquid-dose fraction to inject at each site. Relying upon commercial needles or catheters, the operator must inject each site with a fraction of the calculated dose at a rate which insures a “homogeneous” distribution and deposition of the agents. In addition, needle tips that do not remain steady during injection results in puncturing or injecting unwanted structures.
Needles used in injection systems most often contain a pointed end having a single orifice. This type of needle does not allow for a controlled distribution of an agent, such as a fluid or a particle, within the interstitial medium of the target. Necrotic zones of the tumor as well as the tumor vasculature should be spared. Therefore, agent distribution within a tumor is random and based on uncontrollable convective forces or on perceived tumor “capacitance” for fluid absorption (subjective fill counter pressure, late visualization of fluid backflow that most often cannot be prevented). Similarly, complete dose administration is not guaranteed since backflow cannot be prevented, is difficult to assess, and intravascular administration is not easy to detect. Multiplying the sites of injection or using multi-needle injectors not only increases the probability of injury to tumor structures but also increases the operation time. Moreover, this type of procedure can lessen a patient's tolerance, leading to decrease in patient compliance to repeated procedures.
Current tissue delivery systems for depositing fluid or fluid-like agents and fluid based substances into an entire lesion utilizes multiple needle tips repeatedly inserted into the tissue in order to increase the diameter of induced necrosis/apoptosis. This approach, however, is both time-consuming and difficult to employ in the clinical setting particularly because multiple overlapping treatments must be performed in a contiguous fashion in order to distribute the agent to the entire lesion. Simultaneous use of multiple needles can reduce the duration of application but is difficult for use in narrow passages or endoscopically since it is technically challenging. The development of pronged injection needle electrodes with multiple arrays should enable the creation of larger foci of more homogeneous fluid distribution with a single penetrating site.
In spite of the promise associated with most techniques of direct interstitial fluid-based therapies such as chemoablation of skin, lung, prostate, breast, head and neck, brain tumors, liver tumors, and the potential clinical applications of these techniques, progress has been hampered by the lack of effective means to achieve the overall objective of efficient and reliable agent delivery to target. One of the most significant shortcomings related to the current systems is the inability to achieve reliable and consistent application from subject to subject. Moreover, insuring full dosage of a therapeutic agent administered to the target lesion can not be guaranteed. Significant sources of this variability are due to differences in the technique and skill level of the operator as well as differing physiological characteristics between patients.
Even if the dose amount of agents injected locally into a tumor tissue is usually much lower than systemic administration, low dosage is desirable in order to prevent side effects. Preventing composition flowing out of the target area is critical, as back flow of the agents can result in unintended harm to healthy structures, create complications, or prolong the procedure. The instantly disclosed system and method has the potential of fast and reliable securing method and more efficient delivery and diffusion of the calculated dose of composition directly into the target tissue through a single injection site, while preventing backflow of injected composition through the entry track of the instrument.